Method and apparatus for stripping well pipes



April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 3 Sheets-Sheet 1 FiledApril 15, 1963 FlG.

INVENTOR'.

ms AGENT April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 5 Sheets-Sheet 2 FiledApril 15, 1963 FIG. 6

lNVENTOR:

V. F. FURRY FIG- 3 HIS AGENT April 20, 1965 v. F. FURRY, JR

METHOD AND APPARATUS FOR STRIPPING WELL PIPES 3 Sheets-Sheet 3 FiledApril 15, 1963 FIG. 9

FIG. 7

FIG. ll

FIG. IO

' INVENTORZ V. F. FURRY BY: t

IS AGENT United States Patent 3,179,178 METHGD AND APPARATUS FURSlTREPPlNG WELL FEES Vernon F. Furry, In, Bakersfield, Cali assignor toShell Oil Company, New York, N.Y., a corporation of Delaware Filed Apr.15, 1%3, Ser. No. 273,tlll5 15 Claims. (Ql. Ida-49) This inventionrelatesto a method and apparatus for running pipe in and out of a welland pertains more particularly to a method of inserting into or removingfrom a well a string of pipe which surrounds a second string of pipe ofa smaller diameter or a well tool which must be held in tension in thewell to prevent it from dropping to the bottom of the well.

The operation of inserting a pipe into a well or remov ing it therefrom,when the pipe surrounds a second pipe or an elongated object alreadydisposed within the well, is commonly referred to as stripping.

In an attempt to locate new oil fields an increasing amount of welldrilling has been conducted at offshore locations, such, for example, asof]? the coasts of Louisiana, Texas, and California. As a general rule,the strings of casing in a well, together with the tubing string orstrings, extend to a point well above the surface of the water wherethey are closed in a conventional mannerthat is used on land wells, witha conventional wellhead assembly being attached to the top of thecasing. Attempts have been made recently to provide methods andapparatus for drilling, completing and working over a well wherein boththe well casing-head and the various well components secured thereto orsuspended therefrom .are' located underwater at a depth suiiicient toallow Ships to pass over them. Preferably, the casinghead and itsassociated equipment are located close to the ocean door. In order toinstall equipment of this type underwater in depths greater than theshallow depth at which a diver can easily operate, it has been necessaryto design entirely new equipment for this purpose.

In one such method of drilling offshore wells wherein a wellhead basestructure is positioned on the ocean iloor, strings of pipe, made up ofmany sections of pipe fastened together, are stripped in and out of thewell by the method and apparatus of the present invention.

It is the primary object ofthe present invention to provide a method andapparatus, the apparatus being simplein design and easy to operate,whereby a larger internal diameter pipe may be stripped into a well overa smaller diameter pipe or a well tool of smallerdiameter.

. A further object of the present invention for stripping pipe into anoifshore well from a platform positioned above the ocean surface, whilemaintaining a constant tension on an inner pipe string of smallerdiameter over which the larger diameter pipe string is being stripped.

Another object of the present invention is to provide simple and safeapparatus adapted to be connected to and FIGURE 2;

locked on an inner string of pipe to be held in constant a tension whilean outer string of pipe is stripped over it.

Still another object of the present invention is to provide a method andapparatus for stripping pipe into or out of a well wherein thesuspension apparatus for the pipe is positioned substantially along thecenter line of the pipe at all times.

These and other objects of this invention will be understood from thefollowing description taken with reference to the drawing, wherein:

FIGURE 1 is a longitudinal diagrammatic View illu trating cutawaysections of a derrick together with the hoist systems mounted in thederrick in accordance with the present invention;

FIGURE 6 is a fragmentary isometric View illustrating the locking sleevenormally carried in the connector base of FIGURE 2; and,

FEGURES 7 through 11 are schematic views illustrating the stepwiseoperations of carrying out the method of the present invention.

Referring to FIGURE 1 of the drawing, numerals 11 and 12 representfragments of a well derrick, such for example as the type used indrilling wells, which would extend down to an operational base or fioor13, which may be the floor of a derrick or a floor of a drillingplatform, either stationary or floatable, as used in drilling oilshorewells. The derrick Ill-l2 is provided with a conventional hoist systemincluding a crown block 14, a traveling block 15 provided with a hook15a and fall lines to running to a hoist lea. Secured to the lower endof the traveling block 15 are elevator links 17 which suspend aconventional pipe-engaging elevator 18. The elevator 18 is designed toclamp around the upper end of a larger-internal diameter pipe string 29,or a section thereof, for raising or lowering the pipe string.

The derrick i112 may be also provided with another hoist systemcomprising hoist 21, hoist line 23, sheave 25 and connector element 27carried at the end of the hoist or suspending line 23. In the event thatthe present hoist system is mounted on a floating drilling barge adaptedto move up and down with relation to a wellhead positioned on the oceanfloor, the hoist 21 would be preferably constant tension hoist. r I

A second hoist or suspending line or cable 24, having a loop. 24a at thetop thereof to fit over the hook 15a and be suspended thereby, isprovided at the lower end thereof with a connector element 28 which issimilar to connector element 27. The length of the suspending cable 24is sufficient so that the connector element 28 would be at least belowthe lower end of a section of pipe 20 hanging in the elevators l8.

Positioned substantially axially within the larger-diameter outer pipestring Zlla is a smaller diameter innerpipe string 3t having a connectorbase 31 secured to the top thereof which is adapted to be locked toeither of the con hector elements 27 or 28., The pipe string Ella isillustrated as extending through a hole 32 in the floor of the derrick,and through a spider or rotary table 33 in which slips 3% are wedged inorder to hang the pipe strings 2t? therefrom.

in FIGURE 2,one form of a connector base 31 comprises a body member 35having an upwardly-extending mandrel section 36 of smaller diameter,with a pair of locking or latching lugs 3'7 and 33 formed on or fixedlysecured thereto. The lugs 3'7 and 38 are positioned diametricallyopposite each other on the mandrel 36 and extend outwardly therefrom.

The connector element 27 is illustrated as being provided with anopening 40 in the body thereof for receiving and locking therein onelug, in this case lug 37 of the connector base 31. The hoist cable 23 isfixedly secured to the top of the connector element 27 in any suitablemanner, as by a split thimble 41 and a lead upset 42. The opening 48 ismore clearly shown in the isometric view of FIGURE 4. The upper end ofthe opening 4% is wider, as at 40a, than the lower portion at dill), thebottom of the connector element 27 isbeing.

closed, as at 43, so as to support a locking lug 37 or 38 g of themandrel 36. As shown in FIGURE 5 some of the wider portion 37a of thelug 37 is adapted to pass through the wide opening 40a in the connectorelement 27 while the grooved portion 37b of the locking lug 37 isadapted. to seat within the narrow opening 48b of the connector device27.

To prevent the connector element 27 (FIGURE 2) from becomingaccidentally unlatched from the locking lug 37 of the connector base 31,the connector base 31 is provided with suitable locking means which maytake the form of a sleeve 44 mounted in the top of the body memher35 forrotational movement about the mandrel 36. The locking sleeve 44 isretained in the body member 35 by means of a ring 45 or other suitablemeans. A spring 46 mounted within the body member 35 is adapted to bearagainst a flange 47 carried at the lower end of the sleeve 44 forpressing the flange 47 downwardly against a positioning ball ororienting element 48. These elements are more clearly shown in thedisassembled view of a portion of the connector base as shown in FIGURE6. Here it is shown that the bottom face of the flange 47 is providedwith a pair of diametrically-positioned grooves 50 and 51 which arealigned with the center line of a slot 52 cut in the side of the lockingsleeve 44 which extends downwardly from the top thereof, as illustrated.The sleeve 44 may be provided with one or more holes 53 extendingthrough the wall thereof into which a pin can be positioned for turningthe sleeve. The slot 52 in the locking sleeve 44 should be slightlywider than the widest part of either locking lug 37 or 38 carried at theupper end of the connector base 31. The height of the sleeve would besuch that as shown in FIG- URE 2, the sleeve 44 may be rotated under thelower end 43 of the connector element 27 when it is engaged and with thebottom of the locking lug 37 of the mandrel 36 thus locking theconnector element to the connector base 31. To unlock the connectordevice so that the connector element 27 can be detached from the lockinglug 37, the locking sleeve 44 would be rotated 180, or until the groove50 (FIGURE 6) seated on the ball 48, at which time the slot 52 in thelocking sleeve 44 would be positioned beneath the closed end 43 of theconnector element 27, allowing it to be moved downwardly into the slot52 at which time the enlarged portion 37a of the locking lug would beopposite the wide portion 40a of the opening 40 so that the connectorelement 27 could be removed laterally from the locking lug 37.

The lower end of the connector base 3]. is provided with suitable means,such as screw threads 54, whereby the connector base 31 may be removablysecured to the top of the smaller-diameter inner pipe string 34) (FIG-URE 1). It is to be understood that any other suitable form of a devicefor latching onto the inside or the outside of a pipe may be employedfor securing the connector base 31 (FIGURE 2) to a smaller diametertubular pipe string 30 or other elements over which pipe is to bestripped.

In performing an operation in accordance with the present invention ofstripping a larger internal diameter pipe into a well over a smallerdiameter pipe which is axially movable within the larger pipe, theoperation would start as illustrated in FIGURE 7 with the largerinternal diameter pipe 28a being held by means of slips 34 in a fixedposition within the spider or rotary table 33. At the same time theconnector base 31 (FIGURE 2) would be secured to the top of the smallerdiameter pipe string 30 (FIGURE 7) with the connector element 27 securedto the lower end of hoist line 23, being connected to one lug of theconnector base 31 so that the tension on the cable 23 could hold theconnector base 31 above the upper end of the pipe string 28a. Withconnector element 27 and its hoist cable 23 being employed in thismanner, the other connector element 28 and its cable 24 (FIGURE 7) wouldbe run down another section of pipe 28 which is to be added to pipe 20aalready suspended from slip 34. The elevator 18 would be connected toone end of the pipe section 28 to be added and it would be hoisted tomove into the position shown in FIGURE 8 by means of the main hoistsystem of the derrick. With the new section 24B of pipe suspended inthis position, the connector element 28 extending therethrough would becarried over manually to the locking lug 37 and locked thereon as shownin FIGURE 8. Alternatively, the connector element 28 could be connectedto the connector base 31 prior to moving the pipe section 29 to avertical position over the pipe string 28a. At this time the pipesection 28 and the cable 24 carried substantially concentrically thereinwould be jointly suspended in substantial longitudinal relationship withthe pipe string 29a already in the well, as shown in FIGURE 8. Tensionwould then be applied to cable 24 and its connector element by means ofthe hoist 16a, fall lines 16, traveling block and hook 15a (FIGURE 1),at which time the weight of the inner pipe string 30 would betransferred from connector element 27 to connector element 28.Alternatively, the weight of the inner pipe string 38 may be transferredfrom connector element 27 to connector element 28 by reducing thetension or slacking off slightly on suspending cable 23. With the cable24 and its connector element 28 now supporting the inner pipe string31), the other connector element 27 and its cable 23 are disconnectedfrom the locking lug 38 of the connector base 31 and removed therefrom.

The additional section of pipe 28 is then lowered simultaneouslytogether with the cable 24, connector element 28, connector base 51 andinner pipe string 38 moving lower in the pipe string 28a until thethreads 82 at the lower end of the pipe section engage the threads inthe upper section of the pipe 28a and may be rotated therein, forcoupling the two pipe sections together. After the new section 28(FIGURE 9) was secured to the pipe string 28a, the slips 34 would beremoved (FIGURE 10) while the elevator 18 (FIGURE 1) supported thelarger internal diameter pipe string 20a and lowered it into the well adistance equal to the added pipe section 28, at which time the slips 34would again be inserted around the pipe string 20a to suspend it inplace. The elevator 13 would then be disconnected from the top of thepipe section 20 and the traveling block 15, hook 15a, suspending cable24 and connector device 28 would be pulled up until the inner pipestring had been pulled up through the larger internal diameter pipe adistance to bring the connector base 31 above the larger internaldiameter pipe string Zita as shown in FIGURE 11. The other connectordevice 27 at the end of suspending cable 23 would then be secured to theconnector base 31 and the weight of the inner pipe string 38 would betransferred thereto by slacking off on cable 24 or hoisting on cable 23slightly. By repeating the cycle of operation described, the desiredamount of pipe may be stripped into a well. It may be seen that sincethe pipe section 20 must be positioned vertically above the pipe section20a, the sheave (FIGURE 1) is preferably positioned near the center lineof the derrick. Alternatively, the present method may be practicedwithout use of a hoist 21 for cable 23. Instead a cable 23a may befixedly secured to a temporary cross beam extending between braces 61 onthe derrick, the beam 6'!) being close to the center line of the derrickbut out of line of travel of block 15a.

To remove a larger internal diameter pipe from a well and strip it outof a smaller diameter pipe, the abovedescribed procedure would bereversed. After connector element 28 was secured to the connector base,the block 15a and elevator 18 would be lowered and connected to pipesection 20. The upper pipe section 20 would then be raised together withpipe string 20a by means of elevator 18 (FIGURE 1) and unscrewed andelevated from that section 20a, to expose the connector base 31 asshown. The connector device 27 would then be brought into position andlatched on the connector base 31 and tension applied to its cable 23 orcable 24 being slacked off to transfer the weight of the inner pipestring 30 to cable 23. Connector 28 would then be detached from theconnector base 31, as shown in FIGURE 7, and the connector device 28 andits cable 24 would be pulled out of the pipe section 20, as shown inFIGURE 7, while the other cable 23 and its connector device 27 supportedthe inner pipe string 30.

I claim as my invention:

1. A method of stripping a larger internal-diameter outer pipe stringover a smaller-diameter inner elongated member which is axially movable,said method comprising the sequential steps of (a) temporarilysuspending said larger internal-diameter outer pipe string andconnecting a first suspending element to said inner member to suspendsaid inner member within said larger internal-diameter outer pipestring,

(5) running a second suspending element through a section of largerinternal-diameter outer pipe to be added to the top of said outer pipestring,

(c) jointly suspending and moving said pipe section to be added and saidsecond suspending element carried therein into substantial longitudinalposition above said suspended outer pipe string,

(:1) connecting said second suspending element to said inner member,

(e) transferring the Weight of said inner member from i said firstsuspending element to said second suspending element,

(1) disconnecting said first suspending element from engagement withsaid inner member, s

(g) lowening said larger internal-diameter pipe section into engagementwith said outer pipe string While lowering said inner member in tensionWithin said outer pipe string, and

(h) connecting the pipe section to the pipe string.

2. The method of claim 1 wherein the weight of said inner member istransferred to said second suspending element by applying tension tosaid second suspending element.

3. The method of claim 2 wherein the application of tension to saidsecond suspending element comprises the step of raising said secondsuspending element.

4. The method of claim 2 wherein tension is applied to said secondsuspending element by lowering said first suspending element.

5. The method of claim 1 including the subsequent steps of lowering saidouter pipe string and said inner member simultaneously a distancesubstantially equal to the pipe section added, and again suspending theouter pipe. string against further downward movement.

6. The method of claim 5 including the subsequent step of raising theinner member until the top thereof emerges from the top of the outerpipe string.

7. A method of stripping a larger internal-diameter outer pipe stringover a smaller diameter inner pipe string having at least the lower endthereof positioned within a well, said method comprising the sequentialsteps of (a) fixedly suspending said outer pipe string by engaging theouter surface thereof in a supporting manner,

([2) attaching a connector base to the top of the inner pipe string,

(c) connecting a first suspending cable to said connector base tosuspend said inner pipe string within said larger internal-diameter pipestring,

(cl) running a second suspending cable through a section of largerinternal-diameter outer pipe to be added to the top of said outer pipestring,

(e) jointly suspending and moving said outer pipe section with saidsecond suspending cable positioned substantially concentrically thereininto substantial longitudinal position above said suspended outer pipestring, (f) connecting the lower end of said second suspending cable tosaid connector base,

(g) raising said pipe section and said second suspending cablesimultaneously to suspend the inner pipe string from said suspendingcable,

(h) disconnecting said first cable from said connector base,

(i) lowering and connecting the larger internal-diameter pipe sectioninto engagement with said suspended outer pipe string,

(j) simultaneously lowering said inner and outer pipe strings a distancesubstantially equal to the pipe section added, and i (k) againsuspending outer larger-diameter pipe string free of said smaller innerpipe string.

8. The method of claim 7 including the subsequent step of raising theinner pipe string in suspension until the connector base thereof isabove the top of the outer pipe string.

9. A method of stripping a larger internal-diameter outer pipe stringover a smaller-diameter axially-movable inner elongated member, saidmethod comprising the sequential. steps of (a) fixedly suspending saidouter pipe string from the outer surface thereof, 7

(b) connecting a first suspending element to said inner elongated memberto suspend said inner member therefrom,

(c) loweringsaid first suspending element and said smaller-diameterinner elongated member into said larger internal-diameter outer pipestring a distance substantially equal to the length of a pipe section ofsaid outer pipe string,

(d) engaging in a suspending manner said larger internal-diameter outerpipe string above its suspension point and simultaneously raising saidinner elongated member and said outer pipe string until at least onesection of the outer pipe string is above its previously-suspendedposition,

(e) again fixedly suspending said outer pipe string at a point below theuppermost pipe section thereof,

(7) disconnecting at least one pipe section from the top of said outerpipe string,

(g) raising said disconnected pipe section until at least :the top or"the inner member is exposed,

(h) engaging said inner elongated member with a second suspendingelement positioned outside said disconnected pipe section,

(i) transferring the weight of said inner elongated member from saidfirst suspending element to said second suspending element, and g i (j)disconnecting said first suspending element from said inner elongatedmember.

10. The method of claim 9 including the subsequent steps of moving saidlarge internal-diameter pipe section to one side of said suspended pipestring, and withdrawing said first suspending element from said pipesection.

11. Apparatus for use in well operations for selectively stripping to orfrom a Well a larger internal-diameter pipe string over asmaller-diameter inner elongated member held in tension throughout theoperation, said apparatus comprising (a) an operational and sup-portbase positioned adjacent said pipe string,

(b) hoist means including hoist cable means having a portion arrangedfor vertical movement above said pipe to be stripped out of the well,

(0) connector means secured to the end of said hoist cable means, saidconnector means including,

(d) a first connector of a size adapted to connect to the upper end ofsaid larger internal-diameter outer pipe string,

(2) a connector base removably securable to the upper end of said innerelongated member and a second connector of a size to connect to saidconnector base of said inner elongated member and pass through saidouter pipe string and being of a length sufficient '7 to extend beyondsaid first connector a distance greater than a section of pipe in saidouter pipe string,

(f) independent suspension means mounted adjacent said small-diameterinner elongated member and being of a size to engage it selectively andtemporan'ly secure it against axial movement relative to said largerinternal-diameter outer pipe string, and

(g) slip-type anchoring means for engaging the large internal-diameterouter pipe string to selectively and temporarily secure it relative tosaid base against axial movement.

12. The apparatus of claim 11 wherein said independent suspension meanscomprises a cable having a third connector at one end thereof forengaging the upper end of the smaller diameter inner elongated member.

13. The apparatus of claim 12 including a hoist connected to the otherend of said cable for raising and lowering said third connector.

14. The apparatus of claim 11 wherein said first connector is apipe-engaging elevator secured to a traveling block.

15. The apparatus of claim 14 wherein said second connector includes aflexible cable secured to a traveling block of said hoist means andarranged to depend therefrom in concentric arrangement :Within saidelevator and having means at the lower end thereof for engaging theupper end of said inner elongated member.

References (Iited by the Examiner UNITED STATES PATENTS CHARLES E.OCONNELL, Primary Examiner.

1. A METHOD OF STRIPPING A LARGER INTERNAL-DIAMETER OUTER PIPE STRINGOVER A SMALLER-DIAMETER INNER ELONGATED MEMBER WHICH IS AXIALLY MOVABLE,SAID METHOD COMPRISING THE SEQUENTIAL STEPS OF (A) TEMPORARILYSUSPENDING SAID LARGER INTERNAL-DIAMETER OUTER PIPE STRING CONNECTING AFIRST SUSPENDING ELEMEMT TO SAID INNER MEMBER TO SUSPEND SAID INNERMEMBER WITHIN SAID LARGER INTERNAL-DIAMETER OUTER PIPE STRING, (B)RUNNING A SECOND SUSPENDING ELEMENT THROUGH SECTION OF LARGERINTERNAL-DIAMETER OUTER PIPE TO BE ADDED TO THE TOP OF SAID OUTER PIPESTRING, (C) JOINTLY SUSPENDING AND MOVING SAID PIPE SECTION TO BE ADDEDAND SAID SECOND SUSPENDING ELEMENT CARRIED THEREIN INTO SUBSTANTIALLONGITUDINAL POSITION ABOVE SAID SUSPENDED OUTER PIPE STRING, (D)CONNECTING SAID SECOND SUSPENDING ELEMENT TO SAID INNER MEMBER,